A dog owner who has access to an open field generally prefers to let his canine companion run free. This situation promotes the interests of both parties: the dog reaps the benefits of unrestrained exercise by roaming carefree across the field, and the owner or master relaxes and enjoys this time since he is not chained to his dog. Unfortunately, the dog has an innate tendency to roam too far. When the master calls the dog home, the dog is often too far to hear his master's calls.
Systems have been proposed for remotely communicating with animate objects, such as humans or other animals. For example, U.S. Pat. No. 4,598,272 discloses a dual communication system between parent and child, or between master and pet, in which both parties carry devices containing transmitters and receivers. The child's device also contains an audible alarm. If a parent wants to monitor his child, he transmits a signal to the child's device. The child's device responds by transmitting a return signal. Based upon the strength of the signal, the parent can determine the child's whereabouts. The parent can also actuate the audible alarm on the child's device by transmitting a signal. The alarm is intended to cause an abductor to release the child by frightening him or drawing attention to him.
A communications device that specifically relates to dog collars is disclosed in U.S. Pat. No. 3,336,530 which describes a directional finding system for hunting dogs. Here, a transmitter, affixed to the collar, continuously transmits a signal. The master, equipped with a receiver, determines his location relative to the dog based upon the strength of the input signal.
In U.S. Pat. No. 3,589,337, a system is disclosed which administers an electric shock to a dog. The electric impulse is generated by a transmitter/receiver tandem. Therefore, by remotely transmitting a signal, the master administers the shock directly to the dog. Because this device can only communicate with the dog via an electric impulse, its utility is limited to a deterrent device.
Another deterrent device for dogs is disclosed in U.S. Pat. No. 4,745,882. This device causes a mild shock or unpleasant noise to be administered to a dog as it approaches the walls of a pen or other confined area. The deterrent signal "persuades" the dog to stay within the restricted area.
Systems have also been proposed for identifying inanimate objects. For example, U.S. Pat. No. 4,659,314 discloses a remotely-actuated sounding device for locating magazines. The sounding device, which is attached to a magazine, can be actuated by a transmitter and receiver. More particularly, by transmitting a signal having a preselected frequency, the user actuates the sounding device, which emits an audible sound, thereby guiding him to his magazine.